The present invention relates to output drivers for signal generating circuits, and particularly to a replacement output driver for a signal generating circuit which effects generation of a signal with a frequency different than the original signal produced by the host signal generating circuit before replacement of the original output driver by the output driver of the present invention. Most particularly, the present invention relates to replacement output drivers in a signal generating circuit of a driver board for a test apparatus used with burn-in operations relating to manufacture of semiconductor devices.
An important step in the manufacture of semiconductor devices is burn-in of the devices and testing associated with the burn-in of those devices. Burn-in is an operation by which the manufactured semiconductor devices are situated in an oven and connected electrically to a driver board which is usually situated externally of the oven. The driver board provides signals for powering selected portions of the manufactured devices, which signals serve to test the circuitry of the manufactured devices as well as contribute to the temperature rise associated with the devices during cycling of the oven.
Higher frequencies applied to semiconductor devices during burn-in significantly raise the case temperature of those devices; thus, with a higher frequency drive signal, burn-in time can be reduced. Such a reduction in time allows a consequent realization of increased throughput in manufacturing, and results in increased yield.
The capital expense of an oven and its associated test equipment which incorporates the driver boards for providing signals for burn-in is significantly high. It is, therefore, generally desirable to upgrade existing test equipment, if possible, rather than invest in wholly new equipment in order to realize the reduced burn-in time achievable with higher frequency drive signals during burn-in.
It is, of course, desirable that such upgrading be effected while maintaining the various monitoring and fault-checking signals of the test equipment (which operate using the original frequency signal produced by the test equipment) while still achieving the output via the driver board of the test equipment at a higher frequency, thereby precluding an entire redesign of the test equipment with its associated significant cost.